Seal assembly

ABSTRACT

A seal assembly ( 46 ) for sealing the interface between a shaft ( 16 ) and a bore-defining wall ( 22 ). The seal assembly ( 46 ) comprises a sealing element ( 50 ), a reinforcing insert ( 52 ), and an elastomeric casing ( 54 ). The sealing element ( 50 ) has a shaft-contacting portion ( 56 ) positioned adjacent the shaft ( 16 ) and an insert-engaging portion ( 58 ) positioned substantially parallel to the bore-defining wall ( 22 ). The reinforcing insert ( 52 ) has a seal-engaging portion ( 66 ) positioned substantially parallel to the bore-defining wall ( 22 ) and positioned radially outward from the insert-engaging portion ( 58 ) of the sealing element ( 50 ). The elastomeric casing ( 54 ) surrounds the radially outer sides of the engaging portions ( 58,66 ) of the sealing element ( 50 ) and the reinforcing insert ( 52 ), to thereby urge the insert-engaging portion ( 58 ) of the sealing element ( 50 ) radially inward towards the seal-engaging portion ( 66 ) of the reinforcing insert ( 52 ).

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 (e) to U.S.Provisional Patent Application No. 60/758,874 filed on Jan. 13, 2006.The entire disclosure of this provisional application is herebyincorporated by reference.

GENERAL FIELD

This invention relates generally to a seal assembly and, moreparticularly, to a seal assembly for sealing the interface between ashaft and a bore-defining wall of a housing.

BACKGROUND

An engine, such an automotive engine, can comprise an engine block,pistons and a crankshaft, with the pistons causing the crankshaft torotate about an axis thereby converting linear motion into rotationalmotion. The crankshaft has a front end, a rear end, and a series ofmotion converting elements (e.g., journals, connecting arms, and crankpins) therebetween. A front seal assembly seals the interface betweenthe front end of the crankshaft (or a component, such as a harmonicbalancer, attached thereto) and a bore-defining wall in the front sideof the engine block (or a front cover mounted thereon). A rear sealassembly seals the interface between the rear end of the crankshaft anda bore-defining wall in the rear side of the engine block (or a rearhousing mounted thereon).

SUMMARY

A seal assembly is provided wherein chemical bonding between a sealingelement and a reinforcing insert need not be depended upon to preservethe integrity of the seal structure. Instead, the relative positioningof engaging portions of the seal/insert components, and elastomericcasing positioning therearound, provides a mechanical lock between thecomponents. This eliminates any need to be overly concerned with thechemical-bonding compatibility of the materials used for the sealingelement and the reinforcing insert. The seal assembly can be used, forexample, to seal the interface between the front or rear end of acrankshaft and a bore-defining wall in the engine block (or acover/housing mounted thereon).

More particularly, a seal assembly is provided for sealing the interfacebetween a shaft and a bore-defining wall. The seal assembly comprises asealing element, a reinforcing insert and an elastomeric casing. Thesealing element has a shaft-engaging portion positioned adjacent theshaft and an insert-engaging portion positioned substantially parallelto the bore-defining wall. The reinforcing insert has a seal-engagingportion positioned substantially parallel to the bore-defining wall andpositioned radially outward from the insert-engaging portion of thesealing element. The elastomeric casing surrounds the radially outersides of the engaging portions of the reinforcing insert and the sealingelement and urges the insert-engaging portion of the sealing elementradially inward towards the seal-engaging portion of the reinforcinginsert.

These and other features of the seal assembly are fully described andparticularly pointed out in the claims. The following description andannexed drawings set forth in detail certain illustrative embodiments,these embodiments being indicative of but a few of the various ways inwhich the principles of the invention may be employed.

DRAWINGS

FIG. 1 is a perspective view of the front side of an engine.

FIG. 2 is a perspective view of the rear side of the engine.

FIG. 3 is an isolated view of a front cover for the engine.

FIG. 4 is an isolated view of a rear housing for the engine.

FIG. 5 is a schematic view of the engine's crankshaft and surroundingcomponents.

FIG. 6 is a close-up sectional view of a front seal assembly for thecrankshaft.

FIG. 7 is a close-up sectional view of a rear seal assembly for thecrankshaft.

DETAILED DESCRIPTION

An engine 10 can comprise an engine block 12, pistons 14, and acrankshaft 16. (FIGS. 1 and 2.) A front cover 20, with a bore-definingwall 22, is mounted to the front side of the engine block 12. (FIG. 1and FIG. 3.) A rear housing 24, with a bore-defining wall 26, is mountedto the rear side of the engine block 12. (FIG. 2 and FIG. 4.) Thepistons 14 cause the crankshaft 16 to rotate about an axis 28, therebyconverting linear motion into rotational motion.

The crankshaft 16 has a front end 30, a rear end 32, and a series ofmotion converting elements 34 (e.g., journals, connecting arms, crankpins) therebetween. (FIG. 5.) The crankshaft 16 can include a harmonicbalancer 38 forming an extension of its front end 30. (FIG. 1.) Theharmonic balancer 38 can include, for example, a wheel 40 and arearwardly projecting hub flange 42, with the flange 42 being press-fit,bolted or otherwise attached to the front end 30 of the crankshaft 16.(FIG. 5.) The wheel 40 can be part of a pulley system driving anaccessory belt 44. (FIG. 1.)

A front seal assembly 46 seals the interface between the crankshaft 16and the bore-defining wall 22 in the front cover 20. (FIG. 5.) Morespecifically, in the illustrated embodiment, the front seal assembly 46seals the interface between the flange 42 of the harmonic balancer 38and the wall 22. Before the front cover 20 is mounted to the engineblock 12, the flange 42 is inserted through the bore defined by the wall22 and the seal assembly 46 is pressed (using force directed away fromthe oil side of the engine and toward the air side of the engine) intothe interface between the flange 42 and the wall 22.

A rear seal assembly 48 seals the interface between the crankshaft 16and the bore-defining wall 26 in the rear housing 24. (FIG. 5.) Afterthe housing 24 is mounted to the rear side of the engine block 12, theseal assembly 48 is pressed (using force directed toward the oil side ofthe engine and away from the air side of the engine) into the interfacebetween the rear end 32 of the crankshaft 16 and the bore-defining wall26. A flywheel (not shown), a flex plate, or another pulsation-reducingcomponent may be attached to the crankshaft's rear end 32 after the sealassembly 48 is installed.

Referring now to FIG. 6, the front seal assembly 46 is shown in detail.As was explained briefly above, the front seal assembly 46 seals theinterface between the crankshaft 16 and the bore-defining wall 22 in thefront cover 20. The front seal assembly 46 generally comprises a sealingelement 50, a reinforcing insert 52, and an elastomer casing 54.

The sealing element 50 comprises a shaft-engaging portion 56, aninsert-engaging portion 58, and a connecting portion 60 therebetween.The portions 56, 58, and 60 form a cross-sectional horse-shoe shape,with the radially-inner portion 56 (the shaft-engaging portion) beinglonger than the radially inner portion 58 (the insert-engaging portion).The shaft-engaging portion 56 is positioned substantially parallel tothe crankshaft 16 (or hub flange 42), the insert-engaging portion 58 ispositioned substantially parallel to the bore-defining wall 22, and theconnecting portion 60 is positioned substantially perpendicular to theportions 56 and 58. The sealing element 50 can open towards the oil-sideof the engine block 12 (i.e., the portions 56 and 58 project rearward),as this geometry may facilitate installation of the seal assembly 46.Specifically, if the seal assembly 46 is pressed in the forwarddirection onto the hub flange 42 of the harmonic balancer, itsconnecting portion 60 (rather than the distal edges of its portions 56and 58) will lead the way into the relatively tight seal-receivingspace.

The sealing element 50 can be formed in one-piece and can be made of anappropriate shaft-contacting material. Suitable candidates include, forexample, fluorocarbon polymers, (e.g., polytetrafluoroethylene-PTFE),because they exhibit relatively low friction, are chemically inert, andcan withstand a variety of temperatures. Moreover, because thesematerials have self-lubricating properties, they can often form acoherent and compliant seal with a rotary shaft with little or noadditional lubrication or sealant. In any event, the radially innersurface of the shaft-engaging portion 56 can be provided withappropriate grooves 64 for rotation, such as a triple start spiralgroove. The connecting portion 60, which may also be an insert-engagingportion, can include openings or slots 62 spaced around itscircumference.

The reinforcing insert 52 comprises a seal-engaging portion 66 orientedsubstantially parallel to the bore-defining wall 22, anotherseal-engaging portion 68 oriented substantially perpendicular to theportion 66, and another anchoring portion 70 also oriented substantiallyparallel to the bore-defining wall 22, but positioned radially outwardfrom the portion 66. The reinforcing insert 52 can be made of metal,such as aluminum, steel, stainless steel, copper, brass, titanium,nickel, and alloys thereof. The metal may be anodized, plated, orotherwise treated for increased corrosion resistance. Ceramics or hardplastics may also be possible reinforcing materials in certain sealingsituations.

The insert-engaging portion 58 of the sealing element 50 follows theprofile of the seal-engaging portion 66 of the reinforcing insert 52 andis positioned radially outward therefrom. The connecting portion 60 ofthe sealing element 50 (which, as was indicated above, can also be aninsert-engaging portion) follows the profile of the seal-engagingportion 68 of the reinforcing insert 52. In the front seal assembly 46,the seal portion 60 can be positioned on the air-side (e.g., front side)of the insert portion 68. The openings 62 in the portion 60 form apassageway through the sealing element 50 to the air-side surface of theinsert portion 68.

In the illustrated embodiment, the sealing element 50 appears to becontacting the reinforcing insert 52 in the engaging portions 58/66 and60/68, and this may very well be the case. However, in some instances,an elastomeric skin or other surface coating may be applied to theengaging surfaces. Such an elastomeric skin might form a chemical bondbetween the element 50 and insert 52, however these bonds are usually oflimited strength and durability. In any event, as is explained below, achemical bond between the sealing element 50 and the reinforcing insert52 is not necessary.

The elastomeric casing 54 surrounds the radially outer surfaces of theseal-insert engaging portions 58/66 and occupies the space between thesesurfaces and the bore-defining wall 22. In this manner, the elastomericcasing 54 urges the insert-engaging portion 58 of the sealing element 50radially inward towards the seal-engaging portion 66 of the reinforcinginsert 52. Thus, the sealing element 50 and the reinforcing insert 52need not depend on chemical bonding therebetween to preserve theintegrity of the seal assembly 46. Instead, the relative positioning ofthe engaging portions 58/66 of the seal/insert components 50/52, and theelastomeric casing 54 positioning therearound, provides a mechanicallock between the components. This eliminates any need to consider thechemical-bonding compatibility of the materials used for the sealingelement 50 and the reinforcing insert 52. It also removes the need tohave a skin surrounding the metal insert 52 (and/or the sealing element50) although, as indicated above, such a skin could be used.

The casing 54 can also surround the air-side surfaces of the seal-insertengaging portion 60/68, and passes through the openings 62 in thesealing element 50 to the insert portion 68. These elastomeric passagescan provide a further mechanical lock, as the casing 54 bonds to thereinforcing insert 52. (A casing-insert bond will usually be muchstronger and durable than an insert-seal bond.) The casing 54 can alsoextend into the radially inner surfaces of the sealing element 50 andthe reinforcing insert 52 and/or the casing 54 can form a dirt-excludinglip 72 at the shaft-air-side edge of the seal assembly 46.

The elastomeric casing 54 can be made from a duroplastic orthermoplastic synthetic material, such as epoxy resin, bis-maleimideresin, polyurethane resin, silicone resin, PEEK, PA, PPA, PTFE, PFA,PPS, PBT, PET, PI or PAI. Natural rubber may also be an option incertain instances.

The elastomer material can be molded into the casing 54 andsimultaneously around the sealing element 50 and the reinforcing insert52 previously positioned in the mold cavity. The sealing element 50 canbe provided as a flat disc (with the openings 62 formed therein) andthen formed into the horseshoe shape during the molding process. Thegrooves 64 in the shaft-contacting surface of the sealing element 50 canalso be formed prior to the molding process (e.g., machined or knifedinto the appropriate location on the flat disc), or can be formed duringthe molding process. It may be noted that forming the grooves 64 duringthe molding process may provide improved production uniformity and/oraccuracy. The reinforcing insert 52 can be previously formed (e.g.,machined, stamped, etc.) into its desired shape prior to entering themold cavity. If the elastomer casing 54 is to extend into the radiallyinner surfaces of the sealing element 50 and the reinforcing insert 52(e.g., to form the dirt-excluding lip 72), the chaplets may be used inthe mold apparatus to appropriately direct flow during the moldingprocess.

Referring now to FIG. 7, the rear seal assembly 48, which seals theinterface between the crankshaft 16 and the bore-defining wall 26, isshown in detail. Much like the front seal assembly 46, the rear sealassembly 46 generally comprises a sealing element 76, a reinforcinginsert 78, and an elastomer casing 80. The rear seal assembly 48 can bemade in the same or a similar manner as the front rear assembly 46, bymolding the casing 80 around the sealing element 76 and the reinforcinginsert 78 and forming the horseshoe shape (and grooves 90) of thesealing element 76 during this molding.

The sealing element 76 can be substantially the same as the sealingelement 50, and comprise a shaft-engaging portion 82 (with grooves 90),an insert-engaging portion 84, and a connecting portion 86 (withopenings 88). The horseshoe shape of the sealing element 76 opens to theair-side of the engine block 12 (i.e., the portions 82 and 84 projectrearward), so that the connecting portion 86 leads when the sealassembly 48 is inserted into the space between crankshaft 16 and thebore-defining wall 26. The reinforcing insert 78, like the reinforcinginsert 52, comprises a seal-engaging portion 92 oriented substantiallyparallel to the bore-defining wall 26, another seal-engaging portion 94oriented substantially perpendicular to the portion 92, and an anchoringportion 96 also oriented substantially parallel to the bore-definingwall 26 but positioned radially outward from the portion 92.

The insert-engaging portion 84 of the sealing element 76 follows theprofile of the seal-engaging portion 92 of the reinforcing insert 78 andis positioned radially outward therefrom. The connecting portion 86 ofthe sealing element 76 follows the profile of the seal-engaging portion94 of the reinforcing insert 78. In the rear seal assembly 48, the sealportion 86 can be positioned on the oil-side (e.g., front side) of theinsert portion 94. The openings 88 in the portion 86 form a passagewaythrough the sealing element 76 to the air-side surface of the insertportion 94.

The elastomeric casing 80 surrounds the radially outer surfaces of theseal-insert engaging portions 84/92 and occupies the space between thesesurfaces and the bore-defining wall 26. In this manner, the elastomericcasing 80 urges the insert-engaging portion 84 of the sealing element 76radially inward towards the seal-engaging portion 92 of the reinforcinginsert 78. Thus, as in the front seal assembly 46, the rear sealingelement 76 and the rear reinforcing insert 78 need not depend onchemical bonding therebetween to preserve the integrity of the sealassembly 48.

The elastomeric casing 80 can surround the oil-side surfaces of theseal-insert engaging portions 86/94 and pass through the openings 88 toprovide a further mechanical lock. Additionally or alternatively, thecasing 80 can also occupy regions radially inward of the reinforcinginsert 78 and/or form a dirt-excluding lip 98 at the shaft-air-side edgeof the seal assembly 48.

Although the seal assembly has been shown and described with respect tocertain embodiments, it is obvious that equivalent alterations andmodifications will occur to others skilled in the art upon the readingand understanding of this specification and the annexed drawings. It maybe specifically noted that although the seal assembly 46 and the sealassembly 48 were described in conjunction with a crankshaft 16, they arecertainly not limited to crankshaft applications. The seal assemblies46/48 can be used in many situations where it is necessary (and/ordesired) to seal the interface between a shaft and bore-defining wall.It is further noted that term “shaft” is meant to encompass whateverrotating component is within the bore-defining wall, and is not limitedto a shaft member, per se. For example, the seal assembly 46 seals theinterface between the hub flange 42 of the harmonic balancer 38 and thebore-defining wall 22.

In regard to the various functions performed by the above describedelements (e.g., components, assemblies, systems, devices, compositions,etc.), the terms (including a reference to a “means”) used to describesuch elements are intended to correspond, unless otherwise indicated, toany element which performs the specified function of the describedelement (i.e., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure which performs thefunction. In addition, while a particular feature may have beendescribed above with respect to only one or more of several illustratedembodiments, such feature may be combined with one or more otherfeatures of the other embodiments, as may be desired and advantageousfor any given or particular application.

1. A seal assembly for sealing the interface between a shaft and abore-defining wall, said seal assembly comprising a sealing element, areinforcing insert and an elastomeric casing; wherein the sealingelement has a shaft-contacting portion positioned adjacent the shaft andan insert-engaging portion positioned substantially parallel to thebore-defining wall; wherein the reinforcing insert has a seal-engagingportion positioned substantially parallel to the bore-defining wall andpositioned radially outward from the insert-engaging portion of thesealing element; and wherein the elastomeric casing surrounds theradially outer sides of the engaging portions of the sealing element andthe reinforcing insert and urges the insert-engaging portion of thesealing element radially inward towards the seal-engaging portion of thereinforcing insert.
 2. A seal assembly as set forth in claim 1, whereinthe sealing element has a second insert-engaging portion and thereinforcing insert has a second insert-engaging portions, these secondengaging portions being positioned substantially perpendicular to thefirst engaging portions of the sealing element and the reinforcinginsert, and wherein the elastomeric casing surrounds at least one of theair-side and oil-side of the second engaging portions.
 3. A sealassembly as set forth in claim 2, wherein the second insert-engagingportion of the sealing element is positioned on the air-side of thesecond seal-engaging portion of the reinforcing insert.
 4. A sealassembly as set forth in claim 2, wherein the second insert-engagingportion of the sealing element is positioned on the oil-side of thesecond seal-engaging portion of the reinforcing insert.
 5. A sealassembly as set forth in claim 2, wherein the second insert-engagingportion of the sealing element connects its first insert-engagingportion to its shaft-engaging portion.
 6. A seal assembly as set forthin claim 1, wherein the sealing element includes openings that theelastomeric casing extends through to the reinforcing insert.
 7. A sealassembly as set forth in claim 2, wherein the sealing element includesopenings that the elastomeric casing extends through to the reinforcinginsert, and wherein the these openings are positioned on the secondinsert-engaging portion of the sealing element.
 8. A seal assembly asset forth in claim 1, wherein the elastomeric casing forms a lipadjacent the air-side edge of the shaft-contacting portion of thesealing element.
 9. A seal assembly as set forth in claim 1, wherein thereinforcing insert further comprises an anchoring portion extending fromits first seal-engaging portion.
 10. A seal assembly as set forth inclaim 9, wherein the anchoring portion is positioned generally parallelto the bore-defining wall of the housing.
 11. A seal assembly as setforth in claim 9, wherein the anchoring portion of the reinforcingelement is positioned radially outward from its first seal-engagingportion.
 12. A seal assembly as set forth in claim 1, wherein thesealing element is made of polytetrafluoroethylene (PTFE).
 13. A sealassembly as set forth in claim 1, wherein the sealing element is made inone-piece.
 14. A seal assembly as set forth in claim 1, wherein thereinforcing insert is made of metal.
 15. A seal assembly as set forth inclaim 1, wherein the reinforcing insert is made in one-piece.
 16. A sealassembly as set forth in claim 1, wherein the sealing element is made inone piece and is made of polytetrafluoroethylene (PTFE), and wherein thereinforcing insert is made in one piece and is made of metal.
 17. Incombination, a crankshaft, a bore-defining wall, and the seal assemblyas set forth in claim 1, wherein the seal assembly is installed on oneend of the crankshaft.
 18. The combination set forth in claim 17,wherein the seal assembly is installed on the front end of the sealassembly.
 19. The combination set forth in claim 17, wherein the sealassembly is installed on the rear end of the seal assembly.
 20. Anengine comprising an engine block, pistons, a crankshaft, and a sealassembly as set forth in claim 1, wherein the seal assembly seals theinterface between an end of the crankshaft and a bore-defining wall inthe engine block or in a cover/housing mounted thereto.